97 GT3 Brake Fault - Pre V8 braking system

[GordonMasson]

I have had a long term very intermittent problem with my ABS light coming on and flashing after I have been driving for a few mins. It can then go for weeks without coming on.

You can hear a pump running when I turn the ignition on and then running again every 3 or 4 pushes of the pedal which I think is ok?

 

Today I was driving the car and the ABS light came on solid and the red handbrake light came on solid as well.

I was just heading into a car park and when I pressed the brake there was virtually nothing there.

It wasn’t that the pedal had gone soft. It was just as if there was instantly no friction between the brake and pad.

 

I turned it off for 5 mins and then ran the engine again and everything was fine so I went to drive it 1 mile away to my garage.

Brakes were fine but just before I reached the garage it happened again.

 

I did manage to get Espritmon running on the car a few weeks back and I seem to remember it came back with a code 62….. I think but I could be wrong on that.

 

Any ideas?

[Vulcan Grey]

If the pedal is extra firm and the brakes feel like suddenly there is no friction, then it is most likely the accumulator (or pump) not providing the boost.  It could also be the displacement cylinder or isolation valve acting up along with the Hold solenoid that works with the front brakes.

 

 

Accumulator Pressure Failure Mode

If no boost pressure is available, increasing pedal pressure will move the displacement piston sufficiently

to close its ball valve, but the isolation ball valve will maintain the connection between master cylinder

and brake circuit. Only unassisted non-antilock operation of the front brakes will be available in this

condition.

 

It is possible that the rear brakes are acting up, so your friction level has dropped.  There is the Hold and Release solenoid for the rear brakes.  You can actuate them in Espritmon to see if they are working.

 

Code A062 looks like it wants you to do these steps (in this order)

 

1) INSPECT

 

1 . Fluid level when system is depressurized. To depressurize the unit, turn off the ignition or disconnect

the battery. Then FIRMLY apply and release the brake pedal a minimum of 40 times. The

accumulator is discharged when a hard pedal feel is obtained.

2. Brake lines, brake hoses, master cylinder/booster assembly, pump/accumulator assembly and

brake calipers for leakage.

3.Brake lines, and brake hoses for excessive wear, heat damage, punctures, tears, interference with

other parts, missing clips or holders, poor connections or blockage.

4.Calipers and caliper pins for rust or corrosion.

5.Calipers for proper sliding action.

6.Caliper pistons for movement during brake application and sufficient retraction upon brake

release.

7. Front speed sensors for proper mounting and connections.

 

 

2)G. PUMP MOTOR OPERATION

 

1. Turn off the ignition and depressurise the accumulator.

WARNING: Ensure the accumulator is fully depressurised (apply brake pedal hard and release up to

40 times with ignition off) before removing the accumulator.

Remove the accumulator and install pressure gauge TOOOT1112. Install accumulator on the pressure

gauge adaptor.

2 . Turn on the ignition and allow the pump to run for at least 20 seconds. Turn off ignition and check

for leaks, correcting as necessary. Depressurise the accumulator.

3 . Using the ‘Tech 1’ tool, perform the ‘Total Pump Run Time Test’. Observe the pressure gauge

while turning on the ignition. Is there a sudden jump from 0 to 3500 kPa (0 to 500 psi) or more

almost immediately after the ignition is turned on? (This initial jump in pressure is the amount of

accumulator precharge) If not, and the pump motor is running, perform step 9 of test D ‘Pump Run

Time Too Long’. If the jump in pressure is to less than 4150 kPa (600 psi), replace the accumulator.

4 . Note the pressure at which ‘Tech 1’ indicates “OK” pressure. If this pressure is not within the

11,700 to 13,100 kPa (1700 to 1900 psi) range, replace the accumulator pressure switch. Note

the pressure at which the pump turns off. If it is not within the 17,900 to 20,000 kPa (2600 to

2900 psi) range, replace the accumulator pressure switch. If the pump continues to run but maintains

a constant pressure, perform step 9 of test D ‘Pump Run Time Too Long’.

NOTE: When depressing the brake pedal to cause the pump to run, press the pedal slowly and

carefully until the pump just begins to run. Do not continue to press the pedal after the pump begins

to run, or pump run times which are too short may be missed.

5 . When the pump has stopped, press the brake pedal until the pump begins to run. If this pressure is

not within the 14,150 to 15,850 kPa (2050 to 2300 psi) range, replace the accumulator.

. . .

6 . If: accumulator pressure switch points are al! within range, and; accumulator precharge is greater

than 4150 kPa (600 psi), and; battery voltage is greater than 11.8 volts when the pump is running:

if the total pump run time is greater than 40 seconds, replace the pump and motor assembly.

[GordonMasson]

Thanks Travis

 

"If the pedal is extra firm and the brakes feel like suddenly there is no friction".... describes what's happening perfectly so now its a case of tracking the fault down... I'm guessing its not going to be cheap!

[Vulcan Grey]

If it is the pressure switch, then I'd start here

https://www.google.com/search?q=esprit+abs+pressure+switch+site:www.thelotusforums.com&espv=2&biw=1463&bih=747&sa=X&ei=FraWVe2wJYzVsAXR5L3ABw&ved=0CEUQrQIoBDAB

 

If it is the accumulator, then that is fairly available.  Sounds like your pump is running.

 

You really need Section JF of the Lotus shop manual for the 1993-1997 SE, S4, S4s, GT3, and V8

[PaulEspritGT3]

Gordon,

 

If it does turn out to be the Pressure switch you should read the "delco brakes get them working successfully and well" thread.

 

http://www.thelotusforums.com/forums/topic/69952-delco-brakes-get-them-working-successfully-and-well/?hl=delco

 

I installed this fix 3 years ago and it is still working very well.